Draghead system for use in dredging or the like

ABSTRACT

A draghead visor is configured to attach to an armature along a rotation axis. A biasing assembly attached to the draghead visor is configured for attachment to the armature such that the biasing assembly is positioned to apply a force on the visor in a manner such that a rotational force is applied to the visor around the rotation axis. The biasing assembly may include one or more spring subassemblies, wherein a spring subassembly may include one or more compression spring, extension spring, or torsion spring. The draghead visor may be part of a draghead pulled by a marine vessel.

BACKGROUND

A utility head for attachment to a piece of equipment is constructed for forcible contact with an environment surface. As the utility head is applied to the environment surface, the environment surface exerts a force tending to rotate the utility head in such a way as to minimize destructive contact between the utility head and the environment surface. A counterforce may be applied, tending to balance the force applied by the environment surface.

One example of a utility head is a draghead such as is used in the dredging industry for marine applications. A marine draghead may include a plurality of teeth and is operatively attached to an armature of a structure on a marine vessel. In use, the draghead moves along an underwater surface to loosen material at the underwater surface. The loosened material may then be suctioned and deposited elsewhere at a later time. Water pressure, suction, and gravity work to keep the draghead teeth engaged against the underwater surface. However, the underwater surface exerts forces against the draghead tending to rotate the teeth away from the surface. On some dragheads, a counterforce to the underwater surface forces is applied using active control of a hydraulic cylinder attached to a visor of the draghead. However, the hydraulic control system is complex and expensive, and is not easily retrofitted to existing dragheads and equipment.

SUMMARY

A utility head, for example a draghead, is mounted on a piece of equipment along a rotation axis. A biasing assembly, in the form of one more springs, is mounted between the utility head and the piece of equipment. As the utility head is used to forcibly engage an environment surface, rotational forces are incurred against the utility head about the rotation axis, due to forces applied by the environment surface. The biasing assembly exerts a force on a portion of the utility head so as to counterbalance the rotational forces incurred. The force applied by the biasing assembly is variable and depends on the amplitude and direction of the forces applied by the environment surface. In this manner, the pressure applied to the environment surface may be kept within a desired range.

The foregoing is a summary may contain simplifications, generalizations, and omissions of detail. Consequently, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features of the devices and/or processes described herein, as defined solely by the claims, will become apparent in the detailed description set forth herein and taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a top view of an example draghead utility head.

FIG. 2 illustrates a side view of the example draghead of FIG. 1.

FIG. 3 illustrates a side view of the example draghead of FIG. 1.

FIG. 4A illustrates a top view of an example spring assembly.

FIG. 4B illustrates a side view of the example spring assembly of FIG. 4A.

FIG. 4C illustrates end views of the example spring assembly of FIG. 4A.

FIG. 5 illustrates a top view of another example draghead utility head.

FIG. 6 illustrates a top view of an example spring assembly.

FIG. 7 illustrates an example of a draghead attached to a marine vessel.

FIG. 8 is an image of a prototype draghead according to an example embodiment.

DETAILED DESCRIPTION

A utility head, for example a draghead, is mounted on a piece of equipment along a rotation axis. A biasing assembly is mounted between the utility head and the piece of equipment. As the utility head is used to forcibly engage an environment surface, rotational forces are incurred against the utility head about the rotation axis, due to forces applied by the environment surface. The biasing assembly exerts a force on a portion of the utility head so as to counterbalance the rotational forces incurred. The force applied by the biasing assembly is variable and depends on the amplitude and direction of the forces applied by the environment surface. In this manner, the pressure applied to the environment surface may be kept within a desired range.

A utility head may be removably attached to piece of equipment so that one form of utility head may be replaced with another form of utility head to accomplish a different functionality. A utility head may be embodied in many different forms for different engagements with an environment surface. For example, a utility head may be pulled or pushed along an environment surface, or may be controlled for scooping or grabbing material. Scooping in this context includes scooping with single-sided scoops, dual-sided scoops, other multiple-sided scoops, and clamshell-style scoops. Grabbing in this context includes grabbing by skewering, and grabbing with two or more extensions, where an extension may be straight, curved, or other shape.

A utility head may include passive components such as fixed teeth or blades. For example, a draghead may include one row of teeth, or multiple rows of teeth. A utility head may include active components such as rotating teeth, or drilling or impacting structures. A utility head may also include access and attachment for other mechanisms, such as access ports for suction or blowing mechanisms, or attachments for acoustic equipment. A utility head may also include compartments, such as a hopper compartment or a filter compartment.

In one particular embodiment, the utility head comprises a draghead, which includes a visor upon which the components of the draghead are mounted. The visor includes a visor attachment mechanism for attachment to a piece of equipment along a rotation axis. The visor also includes a biasing assembly attachment mechanism for attaching at least one biasing assembly between the draghead and the piece of equipment. The biasing assembly applies a counterforce to the visor when force is applied to a portion of the draghead. The biasing assembly may include one or more springs.

In an example of a dredging draghead, as the draghead is pulled along an underwater surface, force is applied by material on the underwater surface to rotate the draghead such that teeth on the draghead no longer effectively engage the surface, and the biasing assembly applies a counterforce to the visor to keep the draghead engaged at an effective angle.

FIG. 1 illustrates a top view of one example of a draghead according this disclosure. For context, draghead 100 is shown attached to an armature. Draghead 100 includes a visor 110, a biasing assembly including a spring attachment mechanism 120 and a spring assembly 130, and a draghead attachment mechanism 140. Visor 110 comprises a frame on which components of draghead 100 are mounted.

Spring attachment mechanism 120 may be mounted to visor 110, or alternatively may be an integral part of the construction of visor 110. For example, spring attachment mechanism 120 may be part of a molded visor 110. Spring attachment mechanism 120 is designed to withstand the forces expected to be applied by and against spring assembly 130 in an intended application. Such forces may include compression, extension, or torsion forces.

As shown in FIG. 1, spring attachment mechanism 120 is illustrated as being positioned at the top of draghead 100. In an alternative construction, spring attachment mechanism 120 is positioned elsewhere on draghead 100, for example at a lower rear portion of draghead 100. Further, multiple spring attachment mechanisms 120 may be included on visor 110 for attaching multiple spring assemblies 130. For example, draghead 100 may include a compression spring assembly 130 and an extension spring assembly on different sides of visor 110, which apply complementary forces to draghead 100.

Spring assembly 130 includes one or more compression springs, and a structure suitable to contain the spring(s) in both relaxed and tensioned states. For example, a compression spring assembly 130 is flexible to allow for full or partial compression of the spring, and an extension spring assembly 130 is flexible to allow for extension of the spring. In some embodiments, spring assembly 130 does not allow the spring(s) to return to a fully relaxed state. For example, a spring assembly may “rest” in a partially compressed or partially extended state.

Spring assembly 130 includes one or more mounting area for attaching to spring attachment mechanism 120. Mounting may be achieved, for example, using nuts and bolts, welds, or a hook and loop engagement.

Spring assembly 130 may include one or more spring subassemblies 135, each of which include one or more springs. In the illustration of FIG. 1, spring assembly 130 is illustrated as including two spring subassemblies 135. In other embodiments, spring assembly 130 may include a single spring subassembly 135, or more than two spring subassemblies 135.

Draghead attachment mechanism 140 is configured for rotatable attachment along an axis, labeled “X” in FIG. 1. In one embodiment, draghead attachment mechanism 140 includes multiple aligned holes through which a rod is extended, and the rod is attached to an armature such that the draghead may rotate around the axis of the rod. In the rod embodiment, the multiple aligned holes may be two holes, or may be several holes forming a hinge-like structure. Draghead attachment mechanism 140 may be located near a top of draghead 100, or alternatively near a bottom of draghead 100.

FIG. 2 illustrates a side view of the example draghead 100 of FIG. 1. As illustrated in FIG. 2, spring assembly 130 uses compression springs and is mounted at the top of visor 110, and draghead attachment mechanism 140 is located at the bottom of visor 110 for angular rotation about axis X. Axis X extends vertically out of the illustration page. Rotation about axis X is referred to as clockwise or counterclockwise with respect to the orientation of the illustration in FIG. 2, as shown.

Draghead 100 is shown in FIG. 2 in a position in which the springs of spring assembly 130 are marginally compressed following rotation of draghead 100 around axis X in the clockwise direction. As forces are applied to draghead 110 such that draghead 110 experiences a clockwise force around axis X, spring assembly 130 is compressed and exerts a counterforce such that draghead 100 experiences a counterclockwise force around axis X to balance the clockwise force. Draghead 100 may rotate clockwise around axis X until the springs of spring assembly 130 are compressed as far as is allowed by the design of spring assembly 130.

Spring assembly 130 as illustrated includes attachment points 220 and 230. Attachment point 220 connects to spring attachment mechanism 120. Attachment point 230 connects to the associated piece of equipment such as the armature shown. Also shown in FIG. 2 is an optional suction mechanism 240 that may be attached at an access port 250 of draghead 100.

FIG. 3 illustrates the side view of the example draghead 100 of FIG. 1 in which draghead 100 is rotated clockwise by an angle theta (“θ”) to the point that the springs of spring assembly 130 are fully compressed.

FIG. 4A illustrates a spring assembly 400 that may be used in a spring assembly such as spring assembly 130 in the embodiment of FIGS. 1-3. FIG. 4B illustrates a side view of spring assembly 400 of FIG. 4A; and FIG. 4C illustrates end views of spring assembly 400 of FIG. 4A.

Spring assembly 400 includes two springs 410, multiple through-connectors 420, two ends 430, and nuts 440. Spring assembly 400 is connected at attachment point 220 to the utility head, such as connected to draghead 100 at attachment mechanism 120. Spring assembly 400 is also connected to a piece of equipment, at attachment point 230.

Through-connectors 420 connect ends 430 together, and ends 430 may slide along through-connectors 420 as springs 410 are compressed and decompressed, limited in one direction of travel by the limit of compression, and limited in the opposite direction of travel by mechanical constructs. In the example of spring assembly 400, a mechanical construct on one end may be a head of a through-connector 420, and a mechanical construct on the other end may be a nut 440 attached to threads of through-connector 420. Springs 410 may be attached at one or both of ends 430 within spring assembly 400, or may not be attached to either end 430.

Springs 410 are illustrated in FIGS. 4B, 4C, and 6 as being circular coil springs. Many other types and shapes of spring may be used alternatively. For example, a spring, including spring 410, may be elliptical, square, or other shaped coil spring, a leaf spring, a bow spring, a volute spring, or any other spring or biasing member.

In one embodiment, a spring is a coil of 5160 modified round ASTM A-689 or equivalent material with torsional yield strength of minimum 154.69 KSI, 1.5 inch diameter wire wound right hand with an outside diameter of 10.875 inches. The coil is austenized, quenched and tempered, and shot-peened after winding. The free length of the coil is 47.15 inches and the solid height is 26.53 inches. There are 15.937 working coils and 17.937 total coils. The elastic limit load is approximately 17,616 lbs, with elastic limited deflection of 2.184 inches. At solid height the load is 10,433 pounds, the stress is 91.61 ksi, the deflection is 20.62 inches, and the elastic limit stress is 59.2%. The spring rate is 506.00 pounds per inch, The spring is powder coated and tectyle lubricated and weighs 275 pounds.

In another embodiment, each spring comprises a coil of 5160 round ASTM A-689 or equivalent material with torsional yield strength of minimum 123 KSI, 1.0625 inch diameter wire wound right hand with an outside diameter of 8.5 inches. The coil is austenized and quenched and tempered after winding. The free length of the coil is 28 inches and the solid height is 15.665 inches. There are 13 working coils and 15 total coils. The elastic limit load is 6,414 lbs, with elastic limited deflection of 1.58 inches. At solid height the load is 3,849.8 pounds, the deflection is 12.335 inches, and the elastic limit stress is 60.0%. The spring rate is 312.09 pounds per inch, The spring is powder coated and tectyle lubricated and weighs 92.4 pounds.

FIG. 5 illustrates a side view of another example of a draghead 500 according this disclosure. For context, draghead 500 is shown attached to an armature. Draghead 500 includes a visor 510, spring attachment mechanisms 520 and 525, a spring assembly 530, and a draghead attachment mechanism 540, similar to visor 110, spring attachment mechanisms 220 and 230, spring assembly 130, and draghead attachment mechanism 140, respectively, of FIG. 2.

FIG. 6 illustrates a spring assembly 600 that may be used as spring assembly 530 in the embodiment of FIG. 5. Spring assembly 600 includes one spring 610.

FIG. 7 illustrates one example of how a draghead 100, draghead 500, or other draghead may be attached to a vessel 700 in a marine environment. In FIG. 7, a dredging draghead 710 is attached to an armature 720 of vessel 700. A biasing assembly 730 attaches between draghead 710 and armature 720. Armature 720 is illustrated in an unused position, and also by dotted lines in a position for dredging, leaving a dredged portion 750 and an undredged portion 760 of an underwater surface.

FIG. 8 is a depiction of an exemplary draghead 800 according to an example embodiment of this disclosure. Draghead 800 includes a visor 810, a biasing assembly including two spring subassemblies 820, and a port 830 for optional attachment to a suction mechanism.

Applications for dragheads other than marine dredging are within the scope of this disclosure. For example, other draghead applications include but are not limited to scraping, mulching, mowing, tilling, and harvesting. Further, the draghead is not limited to movement across horizontal surfaces, but may also be used for angled surfaces including vertical surfaces. For example, a draghead may be used for mining operations.

A utility head with biasing assembly has been described in general, and various examples of dragheads with counterforce springs have been provided in detail. Additionally, an example application for a draghead has been illustrated, in the form of attachment to a marine vessel. It will be apparent from the description and drawings that the examples provided are illustrative and not limiting.

Although utility heads with counterforce applied on one rotational axis have been described, some embodiments may employ multiple biasing assemblies for asserting counterforce about multiple rotational axes. For example, a segmented utility head may have multiple segments each with its own rotational axis, and corresponding counterforce biasing assemblies may be employed for each of the multiple segments.

Counterforce biasing assemblies are selected or designed to accommodate the expected range of rotational travel, and the expected magnitude and direction of force applied to the utility head by the environment surface.

The foregoing is not intended to be exhaustive or to limit the present invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the present invention. The embodiments were chosen and described to explain the principles of the present invention and its practical application to enable one skilled in the art to utilize the present invention in various embodiments and with various modifications as are suited to the particular use contemplated. 

1. A draghead visor, comprising: a first attachment structure configured to attach the draghead visor to an armature along a rotation axis; a second attachment structure; and a spring assembly operatively connected to the second attachment structure and configured for attachment to the armature; wherein the second attachment structure is configured such that, when the spring assembly is attached between the second attachment structure and the armature, the spring assembly is positioned to apply a force on the second attachment structure in a manner such that a rotational force is applied to the visor around the rotation axis.
 2. The draghead visor of claim 1, wherein the second attachment structure includes two mounting brackets configured to attach two compression spring subassemblies of the spring assembly.
 3. The draghead visor of claim 1, wherein the spring assembly includes at least one compression spring.
 4. The draghead visor of claim 1, wherein the spring assembly includes at least one extension spring.
 5. The draghead visor of claim 1, wherein the spring assembly includes at least one torsion spring.
 6. The draghead visor of claim 1, wherein the draghead visor is configured for use on a marine vessel.
 7. A utility head, comprising: a visor; an engagement structure configured to forcibly engage an environment surface in a manner such that the environment surface will exert a rotational force against the utility head; and a spring assembly attached to the visor, the spring assembly configured to exert a counterforce against an applied environmental surface rotational force; whereby when the engagement structure comes into contact with the environment surface, the spring assembly responds to variable rotational forces from the environment surface against the utility head by exerting force on the visor, causing counter-rotational forces sufficient to counterbalance the variable rotational forces, and when contact between the engagement structure and the environment surface ends, the spring assembly positions the visor in a rest position.
 8. The utility head of claim 7, wherein the spring assembly is a compression spring assembly.
 9. The utility head of claim 7, wherein the spring assembly is an extension spring assembly.
 10. The utility head of claim 7, wherein the utility head is one of a single scoop and a clamshell-style scoop.
 11. The utility head of claim 7, wherein the spring mechanism is submersible.
 12. The utility head of claim 7, wherein the utility head is a draghead.
 13. The utility head of claim 12, wherein the engagement structure includes one row of teeth and there are no other rows of teeth on the engagement structure.
 14. The utility head of claim 12, wherein the engagement structure includes a suction mechanism.
 15. The utility head of claim 12, wherein the utility head is configured for attachment to a marine vessel.
 16. A marine vessel, comprising: a dredging structure attached to the marine vessel; a draghead operatively connected to a distal segment of the dredging structure at a rotation axis, wherein the draghead includes a visor and one row of dredging teeth attached to the visor; and a biasing assembly operatively connected between the draghead and the dredging structure and configured to at least selectively cause a rotational force on the draghead around the rotation axis, wherein the biasing assembly includes at least one spring assembly.
 17. The marine vessel of claim 16, wherein the spring assembly is a compression spring assembly.
 18. The marine vessel of claim 16, wherein the spring assembly is an extension spring assembly.
 19. The marine vessel of claim 16, wherein the biasing assembly is located towards the top of the draghead.
 20. The marine vessel of claim 16, wherein the biasing assembly is located towards the bottom of the draghead. 